背景典型斑点特征的聚类分析

迷彩是一项重要的目标防护手段,斑点形状设计是进行迷彩设计的基础。首先自动提取背景图像中的明显斑点,然后分析背景斑点周长、面积、伸长度、矩形度、细长度、分散度等特征的统计特性,最后将长度、矩形度、细长度、分散度作为斑点特征向量对提取出的背景斑点进行HCM聚类分析,进而得到背景典型斑点的特征参数。该方法能得到大样本背景图像斑点特征的统计特征,对自动、定量化的迷彩设计具有一定意义。     

The influence of simulation time-resolution on the matching between on-site micro-wind generation and building electric demand

This paper is to investigate the unique impact of simulation time-resolutions on energy matching between on-site micro-wind turbine and household electric demand. The focused indices are on-site electrical energy fraction (OEFe), on-site electrical energy matching (OEMe), and their errors (e_OEF and e_OEM). The methodology consists of parametric analyses with respect to time-resolution levels, averaging methods, demand profiles, turbine capacities, and wind conditions. Two averaging methods are used: ‘Speed Averaging’ and ‘Power Averaging’. With a coarser resolution, two averaging effects have been found. One is an overestimation effect by both the averaging methods, which are more likely to be encountered especially when a high-resolution generation curve frequently crosses intermittent long spikes of a demand curve. The other effect is an underestimation effect on OEFe simultaneously occurring with the Speed Averaging Method under the conditions of (1) a low wind speed and (2) a high unstable wind speed and a low turbine capacity.     

2 500 t/d新型干法水泥生产线热工标定与分析

对AXNW水泥厂2500t/d生产线进行热工标定并分析,该厂熟料产量平均在2850t/d,超过设计产量的14%。系统烧成热耗3308.69k J/kg,高于全国平均水平。C1筒出口温度为290℃,处于国内先进水平,其氧含量达到4.9%,偏高。篦冷机冷却效果欠佳,风室存在风短路现象,直接影响了熟料质量和余热发电量,热回收效率偏低。该烧成系统还有较大的提升潜力,如果通过改进和优化,精细化管理和操作,熟料产能还可以得到进一步的提高,热耗及电耗可明显下降。     

Short‐Term Wind Power Prediction for Wind Turbine via Kalman Filter Based on JIT Modeling

This paper addresses wind power prediction, which is known to be a key technology in energy management systems. In this paper, a 24‐h‐ahead power prediction method using a filter theory is proposed for wind power generation. The prediction method is a simple algorithm. The procedure of prediction consists of two steps: the data processing and the calculation of the predicted values. In data processing, in order to obtain the correlative data from the database, we employ just‐in‐time modeling. In the calculation of the predicted values, we propose a regression model for wind speed and wind power, and the unknown parameters are estimated using a constrained Kalman filter. Moreover, in the procedure used to estimate the unknown parameters, reduction and convergence of the variables are also guaranteed. Finally, the advantages of the proposed method over the conventional method are shown through actual prediction evaluations.     

A method for the determination of turbulence intensity by means of a fast response pressure probe and its application in a LP turbine

This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.     

汽轮机高中压外缸水压试验浅析

在汽轮机的制造过程中,为了确保产品(如高中压外缸)能安全运行,通常需要使用水压试验的方法对主要承压产品进行检测。水压试验的要求高于产品设计要求,其结果将作为承压产品是否合格的重要依据。     

Vibrations of an aramid anchor cable subjected to turbulent wind

The vibration response of an initially pre-stressed anchor cable made of parallel-lay aramid fibres excited by a measured and artificially simulated spatial turbulent wind field is presented in the paper. Results of the analyses of in situ measured wind records are described. For selected data set statistical characteristics and power spectral density functions of the measured wind velocity components are calculated. The wind stochastic velocity fluctuation is modelled as a one-variate bi-dimensional random field. Cross-power spectral density functions, at different point locations are introduced. The combination of the weighted amplitude wave superposition method (WAWS) with the Shinozuka–Deodatis method is used for the analyzed problem. A time-dependent behaviour of the synthetic cable is investigated which is subjected to turbulent wind with large expected oscillations that arise as a result of slackening due to the relaxation effects. A nonlinear transient dynamic analysis is used in conjunction with the finite element method to determine the dynamic response of the cable subjected to turbulent wind at its initially prestressed state and in the selected times after the relaxation effect. The constitutive equation of the relaxation of the aramid cable follows an experimentally obtained law of the logarithmic type. To monitor the dependences of the individual quantities of cable vibration in the phase space, attractors and Poincaré maps are created by sampling the cable’s displacement and velocity at periods of relevant frequencies. Interesting findings based on the response of the cable with rheological properties to turbulent wind are presented.     

CLN 600MW汽轮机组轴系振动治理

文章通过对4号汽轮机组轴系实际振动测量数据以及TN8000机组振动在线监测分析故障诊断系统、生产实时监视系统图形数据的分析,找出了引起4号汽轮机组轴系振动的主要原因,并提出了解决的方法和措施。     

Theoretical insights into the interaction between RunPt13-n (n = 4, 7 and 9) clusters and [BMIM]+ based ionic liquids: Effect of anion

Density functional theory has been performed to systematically study the interactions between Ru_nPt_13-n (n = 4, 7 and 9) clusters and [BMIM]⁺ based ionic liquids. Ionic liquids [BMIM][Br], [BMIM][BF₄], [BMIM][PF₆], [BMIM][CF₃SO₃], and [BMIM][NTf₂] have different effects on the stability of Ru₇Pt₆. Ionic liquids with median size anions of PF₆⁻ and CF₃SO₃⁻ can better improve the stability of Ru₇Pt₆ than those with the small anions of Br⁻ and BF₄⁻ and large anion of NTf₂⁻. Based on negative relaxation energies, the stabilities of Ru₄Pt₉, Ru₇Pt₆, and Ru₉Pt₄ are all enhanced after interacting with [BMIM][CF₃SO₃]. The stability enhanced degree is in agreement with the interaction strength. For Ru₇Pt₆–n{[BMIM][CF₃SO₃]} (n = 1, 2, 3, 4), the interaction between ionic liquid and cluster plays the primary role in stabilizing the cluster in Ru₇Pt₆–[BMIM][CF₃SO₃]. With the increase of the number of [BMIM][CF₃SO₃], the role of the interaction in stabilizing the cluster is getting weaker, while the role of steric protection is getting more important.     

Fracture mechanics approach for failure of adhesive joints in wind turbine blades

Composite components of wind turbine blade are assembled with adhesive. In order to assess structural integrity of blades it is needed to investigate fracture of joints. In this study, finite element analysis based on fracture mechanics was conducted to characterize failure of adhesive joint for wind turbine blade. The cohesive zone model as proposed fracture mechanics approach was verified through the comparison of numerical results with experimental data. Finite element models of wind turbine were developed to predict damage initiation and propagation. Numerical results based on fracture mechanics showed that failure was initiated in the edge of the adhesive bond line due to high level of shear stress prior to reaching the extreme design loading and propagated progressively.